In forming interconnect wiring structures in integrated circuit manufacturing processes, the trend has been to use low-K dielectric insulating materials together with metal damascenes to increase electrical transport speed and take advantage of the processing advantages inherent in a damascene or dual damascene process.
Low-K materials are now routinely required to reduce signal delay and power loss effects as integrated circuit devices are scaled down. One way this has been accomplished has been to introduce porosity or dopants into the dielectric insulating layer, also referred to as an inter-metal dielectric (IMD) layer.
As a result, the need for lower dielectric constant materials has resulted in the development of several different types of organic and inorganic low-K materials. Several different organic and inorganic low-K materials have been developed and proposed for use in semiconductor devices as insulating materials having dielectric constants less than about 3.5.
One problem with low-K materials has been susceptibility of low-K materials to plasma etching damage during an interconnect formation process, where low-K materials may be damaged in terms of overetching to detrimentally alter opening etch profiles as well as degrading dielectric constant properties. The various problems included in interconnect formation processes with low-K materials are exacerbated in higher aspect ratio openings and in dual damascene formation processes where multiple etching steps are carried in the manufacturing process.
To overcome these problems prior art processes have proposed partially filling the via opening with organic resinous material to form a via plug following the via etching process where the via opening extends through lower and upper dielectric insulating (ILD) layers including a middle etch stop layer. The via plug was intended to protect the via opening during the trench etching process. Several shortcomings, including process complexity and cost are associated with the foregoing process. In addition, other shortcomings such as formation of etch residue fences as the trench/via interface, undesired micro-trenching at the bottom portion of the trench, and difficulty in controlling the level of the via plug, have been associated with such a process.
There is therefore a need in the integrated circuit manufacturing art to develop a more reliable and cost effective dual damascene interconnect and method of forming the same.
It is therefore among the objects of the present invention to provide a more a more reliable and cost effective dual damascene interconnect and method of forming the same, in addition to overcoming other shortcomings of the prior art.